Single-Crystal Magnetic-Susceptibility Study of Linear Antiferromagnetic Interactions in CsCuCl3

The single‐crystal magnetic susceptibilities of CsCuCl₃ were measured along the $a$ and $c$ axes in the temperature range 2–140°K. Graphs of $X_{M}T$ vs $T$ indicate that deviations from Curie law behavior commence at approximately 55°K. Least‐squares analysis of the data above 70°K yielded values of the Curie constants of 0.464 and 0.445 for a and $c$ axes, respectively. Structural evidence indicates the existence of linear chains of Cu ions in CsCuCl₃. Comparisons of the experimental magnetic susceptibilities with the calculations of Bonner and Fisher indicate that the one‐dimensional intrachain interactions between nearest‐neighbor copper ions predominate down to approximately 30°K, whereupon, three‐dimensional interactions of copper ions on neighboring chains become important. The exchange integral in the linear region has the value of $\text{J\hspace{0.17em}=\hspace{0.17em}−\hspace{0.17em}4°}\mathrm{K}$ . This explanation is not in disagreement with the powder susceptibility and the heat capacity of CsCuCl₃ measured previously. The single‐crystal susceptibilities exhibit cusps at 10°K, near the heat capacity λ‐type anomaly at 10.4°K.